You can also check the file /var/run/mongodb/mongod.pid for a valid process ID value. Sometimes it might be necessary to create the parent folder so that the PID can be created:

$ sudo mkdir /var/run/mongodb/

You could also check the mongoDB log for other errors:

$ tail /var/log/mongodb/mongod.log

If the mongod service is not active, double-check that folders are named correctly in configuration and service files, and that permissions and ownership are set correctly on those folders. If anything is not named and attributed correctly, then the service will likely not start and note something like the following error:

Like this:

I wrote a data extraction utility which uses PolarSSL to export a Base64-encoded SHA-1 digest of some internal metadata (a string of JSON-formatted data), to help validate archive integrity:

$ unstarch --sha1-signature .foo
7HkOxDUBJd2rU/CQ/zigR84MPTc=

So far, so good.

But now I want to validate that the metadata are being digested correctly through some independent means, preferably via the command-line, so that I can perform regression testing. I can use the openssl, xxd and base64 tools together to test that I get the same answer:

As a note to myself: I end up stripping the trailing newline from the JSON output of unstarch because this is what the PolarSSL library ends up digesting. This very nearly had me doubting whether PolarSSL was working correctly, or whether my command-line test was correct!

Like this:

MacPorts is useful for installing a variety of command-line utilities and programs for Mac OS X. There are others, e.g. Homebrew. After using MacPorts to update a GNU gcc installation, it is useful to select the new revision. Tips were posted to this Stack Overflow thread. Basically, it boils down to two steps: